开发一个简单的P2P应用（图一）" />
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（图1）

public MyTcpListener(int port) : base(port)

{

}

public void StopMe()

{

if ( this.Server != null )

{

this.Server.Close();

} }

}

public class Transfer

{

MyTcpListener tcpl;

public Transfer()

{

OptionsLoader ol = new OptionsLoader();

int port = 8081;

if (ol.Port > 0)

{ port = ol.Port;

} else

{ port = 8081;

} this.tcpl = new MyTcpListener(port);

}

public void TransferShutdown()

{ tcpl.StopMe();

}

public void ListenForPeers()

{ try

{

Encoding ASCII = Encoding.ASCII;

tcpl.Start();

while (true)

{

// 在有连接之前，Aclearcase/" target="_blank" >ccept将处于阻塞状态

Socket s = tcpl.AcceptSocket();

NetworkStream DataStream = new NetworkStream(s);

String filename;

Byte[] Buffer = new Byte[256];

DataStream.Read(Buffer, 0, 256);

filename = Encoding.ASCII.GetString(Buffer);

StringBuilder sbFileName = new StringBuilder(filename);

StringBuilder sbFileName2 = sbFileName.Replace("\", "\\");

FileStream fs = new FileStream(sbFileName2.ToString(), FileMode.Open, FileAccess.Read);

BinaryReader reader = new BinaryReader(fs);

byte[] bytes = new byte[1024];

int read;

while((read = reader.Read(bytes, 0, bytes.Length)) != 0)

{

DataStream.Write(bytes, 0, read);

}

reader.Close();

DataStream.Flush();

DataStream.Close();

}

}

catch(SocketException ex)

{

MessageBox.Show(ex.ToString());

}

} public void DownloadToClient(String server, string remotefilename, string localfilename)

{

try

{

TcpClient tcpc = new TcpClient();

Byte[] read = new Byte[1024];

OptionsLoader ol = new OptionsLoader();

int port = 0;

if (ol.Port > 0)

{

port = ol.Port;

}

else

{

// 缺省的端口号，可以设置为使用的端口号

port = 8081;

}

// 尝试与服务器连接

IPHostEntry IPHost = Dns.Resolve(server);

string []aliases = IPHost.Aliases;

IPAddress[] addr = IPHost.AddressList;

IPEndPoint ep = new IPEndPoint(addr[0], port);

tcpc.Connect(ep);

// 获得流对象

Stream s = tcpc.GetStream();

Byte[] b = Encoding.ASCII.GetBytes(remotefilename.ToCharArray());

s.Write( b, 0, b.Length );

int bytes;

FileStream fs = new FileStream(localfilename, FileMode.OpenOrCreate);

BinaryWriter w = new BinaryWriter(fs);

// 读取流对象，并将其转换为ASCII码

while( (bytes = s.Read(read, 0, read.Length)) != 0)

{

w.Write(read, 0, bytes);

read = new Byte[1024];

}

tcpc.Close();

w.Close();

fs.Close();

}

catch(Exception ex)

{

throw new Exception(ex.ToString());

} } }

}